Vinyl resin compositions stabilized with lead chloride-lead silicate complexes



VINYL RESIN COMPOSITIONS STABILIZED WITH LEAD CHLORIDE-LEAD SILICATE COMPLEXES John G. Hendricks, Boonton, N. J., and Adrian R. Pitrot,

Unlondale, N. Y., assignors to National Lead 'Company, New York, N. Y., a corporation of New Jersey No Drawing. Application March 23, 1956 Serial No. 573,322

7 Claims. (Cl. 260 45.75)

This invention relates to vinyl resin compositions and more particularly to such compositions stabilized withv respect to their-resistance to the action of light and heat 1 It iswell-known that vinyl resin compositions are sensitive to. the-action oflight andoheat and that the acid degradation products produced by such action react to effect deterioration of*the*resin composition. This deterioration; primarily evidenced by color changes in the resin composition, which are in themselves undesirable, also seriously affects other physical characteristics of the resins such as flexibility and tensiljeistrength. Since the resincompositions are necessarily exposed to heat during compounding and processingand tolight during aging, it is desirable toincorporate agents which tendto stabilize, the physical properties of the resin compositions. r .Basic leadsalts of v arious kinds have heretofore been employed :as stabilizing; agents for inyl resin compositions. Among such basic lead salts may be mentioned, for gexample,;dibasic,lead phthalate, dibasic lead phosphite, basic: carbonate White lead, basic silicate'whi'te lead and tri-ba'sic lead sulfate, among others. While such basic lead salts have been: quite successful as stabilizing agents,: and have gained wide popularity in the trade for thispurposertheynevertheless sufier from certain disadvantages. In. some instances these products are too reactivein that they. react-with organic colorants and with plasticizers 1 leading to discoloration under severe conditionsof servrq [the moisture resistance of some of the basic lead stabilizers is.. inadeguate, under; certain conditions, to achieve desired electrical properties after long-term water immersion, lnaddition, many of the above mentioned materialshave high specific gravities which is undesirable in manyapplications, and are manufactured from rather costly. raw materials which limit their use in applications where cost is critical.

It is an object of this invention, therefore, to provide improved vinylj halide" resin compositions stabilized against the fleflfectsof light and heat. Another object is to provide stabilized vinyl halide resin compositions in inertness toward 1 an h r' is fi, rnpositions having economically manufactured and sold. v

Broadly, this inventioh cbntemplates a vinyl halide resin containing a basic lead chloride-lead silicate complex as stabilizer therefor. "*In a" particular desirable ernbo ent, this'finyention contemplates avinyhhalide resin orirpositi'onfcontainingfaboutllj to 20% by weight, based on the 'resingoifa basic "lead chloride-lead silicate a em r s i din ou 13 1. ad calculated 'as 'PbO', fr'omfabolut .to

a o a lated as SiO and frbmaboutl i .cgi kiulatedbaim- If r ad'chloride-lead.silicate complexes u r 2,874,145 a Pa n s? F b-.1?! 1:2

described and bir hed-1hr neniriso. 2.31m;

un fz a'i isgfter; E; Bartomjiformed by heatingto} The basic'lead chl ride-Ieads'ilicate hen; 's'heuiq' preferably be present ,in amount between 0.5 and" by weight, fbasedzon the resin.- Amoiihts' 'lower th an about 0.5%; although they exhibit somebeneficial efiect;

donot intgeural exert ,suflicientistabiliz ng action jto provide" acomrn'er'cially acceptable product: unless other stabilizers are used in' conjunction therewith, "A'mou'nt s' over 20% of the lead chloride-lead'silicateconiplex, on the other hand, are notiordinarily desirable, as they merelyload the resin with large amounts of solids which do no ser e y d itien s ab n' pl r'o e- W h- .the stated 'rangej optimum results are usually obtained using amounts ,of 1 ,5 1 chloride-lead silicate complex be; tween 2 and 7%,"based on the w eightgof theresin y th rm fY iy fha d i ih m nljtqiin l de the various vin'yl fiesin compounds and"combinations known to the art which normally include vinyl halide such as polyvinyl chloride; vinyl resins producedkby Tcon jointly. polymerizing .a .vinyl halide with viny'l acetate or i other. .vinyl .ester; vinyl. resins produced I by conjoint V I polymerization with an,acrylic compouncl as tor, in-

" stanceLethyl m'ethacrylate, orimeth'yl metliacrylate; and

in a beaker and premix co polynifers, of i a vinyI 3 halide. with: other vinyl halide "1 ratios-: 111;: iii es -Se s-wby molding 'in'a' '30 minute cycle at 320"F'. Heatstability studies were; conducted by exposing test specirnensiat 300 Ef in a circulating air oven. In several instancesithe extent of degradation wasfo1lowed by notingathe'decrea'se in reflectance, due to color forma- V tionyus'ing'a Hunter reflectometer with a blue tilter.

. ing l'ead chloride ead rmblf f. A l iil'e r de-leadsilica e;pqmiaextrzasinreg pared by s'lurrying-lG-parts-of litharge -(Pb0)-and-l6 parts of silica in {water and adding to"tne"'s1iiny""r. 1 parts ofhy'drogen chloridein theform'o'f'a'37% aqueous solution. When the reactionwas complete'the slurry was dsw ts d n i te en t e filter r k was ea ed-. approximately 490 C d au wed to safer; The result; ica't compl i i ha'd'the fol g sition Lead bind Silica tjsiOzle I I re a mixtureof compounds whichjupon eating'fprovi eJead oxideJSiIica and has.) gen, said halogen being in combination with a cation; which is volatilized at the temperatureofheating' I This complex was incorporated into a vinyl resin composition as follows:

A plastic composition consisting of 100 grams of polyvinylchloride resin and 50 grams'of di-Z-ethylhexyl phthalateplasticizer was processed according to the processing method described above. 'A similar composition to which 5.0 grams of'ba'sic lead chloride-lead silicate complex 'stabilizerhad beenradded was processed in the same way.

After press polishing at 320 F. the 70-mil sheet of the u'nstabilized composition was yellow-amber in color. Uponexposure to 300 F. in a circulating air oven it turned black in one hour. The composition stabilized with the basic lead chloride-lead silicate was light cream in 'color a fter the press polishing operation and showed no appreciable color change after 7 hours exposurein a circulating air' oven at300 F.

Six-mil films of these compositions were mounted out of doors on test fences in the Long Island, New York, area to compare their light'stability. After two weeks exposure the unstabilized film had spotted and become very tacky indicating that appreciable degradation had occurred. After 1 month exposure it was severely discolored. The film stabilized withthe basic lead chloridelead silicate complex showed ,no appreciable change after 1 month exposure.

Example 2 1 Percent Lead oxide (PbO) 80.8 Silica .(SiO,) 1 14.2 Chlorine (Cl). 5.0

Two plastic compositions were prepared consisting of l OO grams of polyvinyl chloride resin,'50 'gramsof ParaplexG-SO, which is a commercial high molecular weight TABLE II.HEAT STABILITY OF STABILIZED VINYL COMPOSITIONS Percent refiectance Hunter reficctometcr Hours at 300 F.

Basic lead Bnsic chlorideslllcate lead silicate white lead The results set forth in Table II indicate that basic lead chloride-lead silicate complexes according to this invention provide substantially improved heat stability over the commercial basic silicate of white lead.

Example 4 Two vinyl electrical insulation compounds were prepared from 100 grams of polyvinyl chloride resin, 50 grams of di-2-ethylhexyl phthalatc plasticizer, 10 grams of electrical grade clay and 0.5 gram of stearic acid lubricant. In one composition 7 grams of basic lead chloride-lead silicate complex stabilizer according to Example 2'was employed, while in the second composition 7 grams of basic silicate white lead stabilizer was added. These compositions were processed into 70-mil press-polished sheets and volume resistivities at 50 C. determined.

' The formulation stabilized with basic lead chloride-lead polyester marketed .as a plasticizer, by the Rohm and Haas Co.,"Philadelph ia, Pa., and Sgj'rams of stabilizer. The stabilizer additive was variedjas follows: (1 basic carbonate white lead, and (2) the above basic lead chloride-lead silicatecomplex. Processing was as described above. 70-mil press-polished sheets of these compositions were teist'edfor heat stability at 300 F. in a circulating air oven. 7 Hunter refiectometer reading using the ,blue'filt'erwere, taken on the exposed samples with theresults givenin TableI. H p g nTABLEL-HEAT STABILITY OF'STABILIZED VINYL silicate had a volume resistivity of 61x10 ohm-cm, while the volume resistivity of the composition stabilized with basic silicate white lead was 38x10 ohm-cm.

Example 5 Approximately 30 grams 'each of the basic lead chloride-lead silicate complex of Example 2 and basic silicate of white lead were accurately weighed into shallow ,glass dishes and placed in a bell jar containing water at 25 C. The samples were removed at intervals, weighed and the percent gain in weight due to absorption of water determined. The results of'this test are given in Table III. TABLE IIIr-MOISTURE ABSORPTION OF VINYL STABI- LIZERS Percent gain in weight Stabilizer 1 day 4 days 10 days Baslc lead chloride-lead silicaten 0. 17 0.20 0. 34 Basic silicate'white lead 0. 40 0.68 1. 02

assess".

,OOMP O SITIO NS Percent reflectance,- V, 7 Hunter reflectometer .Honrs at 3009B. V i r V Basie car Baslclcad i bonate chloride- 7, whlte lead lead silicate Example3;

Two compositions were prepared and tested as in Example 2 They consisted of 100 grams of polyvinyl chlorideresi'n, 25 grams of tricresyl phosphate plasticizer, 25 grams of Paraplex G-25, another commercial polyester plasticizer, supplied by the Rohm and Haas Co.,

Thus. the basic, lead chloride-lead silicatestabilizers, after 10 'days at high humidity, absorbs only about one third as much moisture as basic silicate white lead. This indicates that vinyl resins stabilized with basic lead chloride-lead silicates can be expected to exhibit superior moisture resistance. 1 The following example substantiates this expectation.

Example 6 Two electrical compositions were prepared from polyvinyl chloride-vinyl acetate (95:5) copolymer resin. In onecase the compound contained 3% basic silicate of white lead and inthe second compound 3% basic lead chloride-lead silicate stabilizer was employed. These compositions were extruded onto copper wire and the wire immersed in water for a period of 18 weeks after which time the electrical properties were'determined.

and 5' ramsot stabilizer; In this case, the stabilizer additive varied between (1) "the basic leadchloride lead siltcatecr Example 2, and 2 basic 'siliqatefwhite The; compound stabilized with basic silicate of white lead had a resistivity of megohms per 1000 ftpof wire. The insulation stabilized with basic lead chloride-lead silicate had a resistivity of 140 megohms per 1000 ft. of wire.

It is apparent that the present invention provides vinyl halide resin compositions which are substantially improved with respect to their resistance to the effects of heat and light. A variety of plasticizers, coloring and modifying agents may also be employed in these compositions as will be understood by those skilled in the art.

While the present invention has been described with reference to certain specific embodiments and illustrated by means of certain examples, no undue limitations are to be reduced therefrom, and the invention is not to be limited except as set forth in the appended claims.

We claim:

1. A' polyvinyl halide polymer composition containing from about 0.5 to 20%, based on the weight of said polymer, of a basic lead chloride-lead silicate cocalcined composition, said composition comprising from about 30 to about 90% total lead calculated as PhD, from about 5 to about 65% silica, calculated as SiO and from about 1 to about 6% chlorine, calculated at C1.

2. A polyvinyl halide polymer composition containing, as stabilizer therefor, from about 0.5 to 20%, based on the weight of said polymer, of a basic lead chloride-lead silicate cocalcined composition, said composition comprising lead oxide, silica and chlorine.

3. A polyvinyl halide polymer composition comprising from about 2 to about 7%, based on the weight of said polymer, of a basic lead chloride-lead silicate cocalcined 6 composition, said composition comprising from about 30 to about 90% total lead calculated as PhD, from about 5 to about 65% silica, calculated as SiO and from about 1 to about 6% chlorine, calculated as Cl.

4. The process of stabilizing a polyvinyl halide polymer composition, which comprises incorporating therein a basic lead chloride-lead silicate composition, said cocalcined composition comprising from about to about 90% total lead calculated as PhD, from about 5 to about silica, calculated as SiO and from about 1 to about 6% chlorine, calculated as C].

5. Process according to claim 4, in which said basic lead chloride-lead silicate cocalcined composition is incorporated in amount between about 0.5 and about 20% based on the weight of said resin.

6. Process according to claim 4, in which said basic lead chloride-lead silicate cocalcined composition is present in amount between about 2 and about 7%, based on the weight of said resin. 7

7. A polyvinyl halide polymer containing, as stabilizer therefor, a cocalcined composition consisting essentially of basic lead chloride and lead silicate.

References Cited in the file of this patent UNITED STATES PATENTS 

2. A POLYVINYL HALIDE POLYMER COMPOSITION CONTAINING, AS STABILIZE THEREOF, FROM ABOUT 0.5 TO 20%, BASED ON THE WEIGHT OF SAID POLYMER, OF A BASIC LEAD CHLORIDE-LEAD SILICATE COCALICINED COMPOSITION, SAID COMPOSITION COMPRISING LEAD OXIDE, SILICA AND CHLORINE. 